Gear motor activating a motor vehicle functional member

ABSTRACT

A geared motor is used control the movement of a vehicle member, such as a window. A reducer casing is arranged at one end of the motor and includes a sensor assembly for detecting the speed and direction of rotation of the motor. The sensor assembly includes a coded magnetic wheel and Hall effect cells that arc positioned between the wheel and a member for concentrating magnetic flux. The Hall effect cells are placed opposite from a lateral face of the wheel and are spaced apart from one another. Output from the cells is sent to a processor to determine the speed and direction of rotation of the motor.

The present invention relates to a geared motor for activating afunctional member of a motor vehicle.

Numerous geared motors of this type are already known in the prior art,which comprise a direct-current electric motor, at the end of which isarranged a reducer casing, in which are arranged means for detecting thespeed and direction of rotation of the motor, the said means comprisinga coded magnetic wheel associated with the output shaft of the motor andat least two Hall effect cells which are offset relative to one anotherand the output of which is designed to be connected to signalprocessing/conditioning means.

Such geared motors are used, for example, for ensuring the activation ofelectric operated windows, electric operated sliding roofs or the likeof motor vehicles.

It is necessary, for various reasons, to know the speed and direction ofrotation of this motor, in order to control the functioning of thelatter.

Means have therefore been installed in these motors which make itpossible to record these parameters using a coded magnetic wheelfastened, for example, to the output shaft of the motor, this codedmagnetic wheel being associated with at least two Hall effect cells.

Reference may be made, for example, to the documents U.S. Pat. Nos.4,857,784, 5,422,551 and 5,500,585 which describe such structures.

However, in all the geared motors of the prior art, the Hall effectcells are arranged opposite the peripheral edge of the coded magneticwheel and in alignment with the latter.

This arrangement, then, has some disadvantages, particularly in terms ofthe accuracy required for mounting these Hall effect cells and of theresulting bulk of the geared motor.

In fact, it is known that, in order to function correctly, these Halleffect cells must be arranged with relatively high accuracy in relationto the coded magnetic wheel, so that, in order to obtain such accuratepositioning, it is necessary for the manufacture and assembly of thegeared motors to be controlled accurately.

Moreover, arranging the Hall effect cells in the extension of the codedmagnetic wheel increases the radial bulk of this geared motor.

The object of the invention is, therefore, to solve these problems.

For this purpose, the subject of the invention is a geared motor foractivating a functional member of a motor vehicle, of the typecomprising a direct-current electric motor, at the end of which isarranged a reducer casing, in which are arranged means for detecting thespeed and direction of rotation of the motor, the said means comprisinga coded magnetic wheel associated with the output shaft of the motor andat least two Hall effect cells which are offset relative to one anotherand the output of which is designed to be connected to signalprocessing/conditioning means, characterized in that the Hall effectcells are placed opposite at least part of a lateral face of the codedwheel between the latter and means for concentrating the magnetic flux.

The invention will be better understood with the aid of the followingdescription given purely by way of example and made with reference tothe accompanying drawings, in which:

FIG. 1 shows a partly sectional diagrammatic view of an activatinggeared motor according to the invention; and

FIG. 2 shows a front view of an exemplary embodiment of means forconcentrating magnetic flux which are involved in the construction ofsuch a geared motor.

FIG. 3 shows a schematic view of an exemplary embodiment of a connectorand Hall effect cells connected to signal processing/conditioning means.

FIG. 1 shows, specifically, a geared motor for activating a functionalmember of a motor vehicle, the said motor being designated by thegeneral reference 1.

Such a geared motor comprises, in general terms, a direct-currentelectric motor, designated by the general reference 2, at the end ofwhich is arranged a reducer casing designated by the general reference3.

The casing may, for example, be produced from plastic, and means fordetecting the speed and direction of rotation of the motor are arrangedin the latter.

These means are designated by the general reference 4 in this figure.

In fact, these means may comprise, in the conventional way, a codedmagnetic wheel, designated by the general reference 5, associated withthe output shaft 6 of the motor 2, and at least two Hall effect cellswhich are offset relative to one another and the output of which isdesigned to be connected to signal processing/conditioning means 13 (seeFIG. 3) as is known in the art.

FIG. 1 shows a single Hall effect cell, the latter being designated bythe general reference 7.

According to the invention, the Hall effect cells are placed opposite atleast part of a lateral face of the coded wheel 6 between the latter andmeans for concentrating the magnetic flux, which are designated by thegeneral reference 8 in this figure.

It would be appreciated, then, that, instead of being arranged oppositethe peripheral edge of this coded wheel, as in the prior art, in thegeared motor according to the invention these Hall effect cells arearranged opposite a lateral face of this wheel.

In order to allow the optimum functioning of these cells, it is thennecessary to provide means for concentrating the magnetic flux which arelocated behind these cells in relation to the coded magnetic wheel.

In fact, the Hall effect cells and the flux concentration means may bearranged level with the peripheral edge of this coded wheel, asillustrated.

These means for concentrating the magnetic flux 8 may, for example,comprise at least one washer made of magnetic material, such as thatillustrated in FIG. 2.

This FIG. 2 shows, specifically, the flux concentration washer 8 whichis open at one of its ends in order to make it easier to mount it aroundthe shaft of the motor, and which, at its other end, comprises means forfastening to the rest of the reducer casing.

These fastening means may, for example, comprise a hole 9 in thiswasher, the said hole being designed to engage around a stud located onthe rest of the casing, in order to ensure the fastening of this washer.

Other embodiments of these means for concentrating the magnetic fluxmay, of course, be considered.

For example, the Hall effect cells 7 may be carried by a connector forconnecting the motor to the rest of the circuits of the vehicle.

This connector is designated by the general reference 10 in this FIG. 1and comprises, for example, a printed-circuit board, designated by thegeneral reference 11, to which are fastened, for example, the Halleffect cells 7 and, it appropriate, means for feeding these and meansfor processing/conditioning the output signals from these, ofconventional type.

For this purpose, the reducer casing 3 comprises at least one well forreceiving this connector, this well being designated by the generalreference 12.

The reducer casing 3 may comprise two opposite wells 12, 12′ making itpossible to ensure that the connector is received respectively in theupper part or in the lower part of the said casing, in order to adaptthe configuration of the geared motor obtained to the configuration ofthat part of the vehicle which is intended for receiving this gearedmotor.

Conventionally, the connector 10 and the reducer casing 3 may comprisemeans for elastic snap-in attachment shown schematically at 14, and agasket 15 may be arranged between the connector and the casing.

Other embodiments of this geared motor may, of course, be considered.

It will be appreciated, then, that the geared motor according to theinvention has some advantages, as compared with the geared motors of theprior art, inasmuch as the special arrangement of the hall effect cellsmakes it possible, on the one hand, to reduce the radial bulk of thegeared motor and, on the other hand, to achieve accurate detection ofthe direction and speed of rotation of the motor by means forconcentrating the magnetic flux being associated with these cells.

What is claimed is:
 1. Geared motor for activating a functional memberof a motor vehicle comprising a direct-current electric motor (2), areducer casing (3) arranged at one end of said motor and including means(4) for detecting the speed and direction of rotation of the motor, thesaid means comprising a coded magnetic wheel (5) associated with anoutput shaft (6) of the motor and at least two Hall effect cells (7)which are offset relative to one another and the output of which isdesigned to be connected to means for signal processing/conditioning theoutput, characterized in that the Hall effect cells (7) are placedopposite at least part of a lateral face of the coded wheel (5) betweenthe wheel and means (8) for concentrating magnetic flux.
 2. Geared motoraccording to claim 1, characterized in that the Hall effect cells (7)and the means for concentrating the magnetic flux (8) are arranged levelwith the peripheral edge of the coded wheel (5).
 3. Geared motoraccording to claim 1, characterized in that the means for concentratingthe magnetic flux comprise at least one washer (8) made of magneticmaterial.
 4. Geared motor according to claim 1, characterized in thatthe means for concentrating the magnetic flux comprise means (9) forfastening to the rest of the reducer casing (3).
 5. Geared motoraccording to claim 1, characterized in that the Hall effect cells areconnected to a connector (10) for connecting the motor to the rest ofthe circuits of the vehicle.
 6. Geared motor according to claim 5,characterized in that the Hall effect cells (7) are fastened to aprinted-circuit board (11) which is connected to the connector (10) andon which are arranged the means for processing/conditioning the outputsignals from these.
 7. Geared motor according to claim 5, characterizedin that the reducer casing (3) comprises at least one well (12) forreceiving the connector (10).
 8. Geared motor according to claim 7,characterized in that the reducer casing (3) comprises two oppositewells for receiving the connector (10) in the upper part or the lowerpart of the said casing.
 9. Geared motor according to claim 5,characterized in that the connector (10) and the reducer casing (3)comprise complementary elastic attachment means.
 10. Geared motoraccording to claim 9, characterized in that a gasket is arranged betweenthe connector (10) and the reducer casing (3).
 11. A motor apparatus forcontrolling movement of a vehicle member comprising: a motor having anoutput shaft defining an axis of rotation; a reducer casing supported atone end of said motor; a non-contact sensor assembly for detecting speedand direction of rotation of said motor including a coded magnetic wheelmounted for rotation about said axis and at least one Hall effect cellfixed relative to and placed opposite at least part of a lateral face ofsaid wheel; and a magnetic flux concentration member mounted on anopposite side of said Hall effect cell from said wheel wherein said Halleffect cell generates a signal that varies with magnetic flux as saidwheel rotates about said axis.
 12. An apparatus according to claim 11wherein said magnetic flux concentration member partially extends aroundsaid output shaft and is mounted to said casing.
 13. An apparatusaccording to claim 11 including a processor for receiving said signal todetermine the speed and direction of rotation of said motor.
 14. Anapparatus according to claim 11 wherein said sensor assembly is mountedwithin said casing.
 15. A motor apparatus for controlling movement of avehicle member comprising: a motor having an output shaft defining anaxis of rotation; a reducer casing supported at one end of said motor; anon-contact sensor assembly for detecting speed and direction ofrotation of said motor including a coded magnetic wheel mounted forrotation about said axis and at least one Hall effect cell fixedrelative to and placed opposite at least part of a lateral face of saidwheel to generate a signal that varies with magnetic flux as said wheelrotates about said axis; a connector supported by said casing andextending inwardly toward said axis wherein said Hall effect cell ismounted on said connector; and a magnetic flux concentration memberpositioned on an opposite said from said connector than said wheel. 16.An apparatus according to claim 15 wherein said connector is a printedcircuit board for directing the signal to a processor.
 17. An apparatusaccording to claim 11 wherein said at least one Hall effect cell is aplurality of Hall effects cells placed opposite at least part of saidlateral face of said wheel and spaced apart from one another.